Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy

TL;DR

This study uses phase-resolved emission spectroscopy from Hubble to map the thermal structure of the highly-irradiated exoplanet WASP-43b, revealing significant temperature variations and atmospheric properties.

Contribution

It provides the first detailed thermal map of WASP-43b's atmosphere using phase-curve data, highlighting temperature variations and hot-spot offsets.

Findings

Large day-night temperature differences at all altitudes

Temperature decreases monotonically with pressure

Derived Bond albedo of approximately 0.18

Abstract

Exoplanets that orbit close to their host stars are much more highly irradiated than their Solar System counterparts. Understanding the thermal structures and appearances of these planets requires investigating how their atmospheres respond to such extreme stellar forcing. We present spectroscopic thermal emission measurements as a function of orbital phase ("phase-curve observations") for the highly-irradiated exoplanet WASP-43b spanning three full planet rotations using the Hubble Space Telescope. With these data, we construct a map of the planet's atmospheric thermal structure, from which we find large day-night temperature variations at all measured altitudes and a monotonically decreasing temperature with pressure at all longitudes. We also derive a Bond albedo of 0.18 +0.07,-0.12 and an altitude dependence in the hot-spot offset relative to the substellar point.